Speed-control system for electric traction-motors.



J. E. HASCHKE.

SPEED CONTROL SYSTEM FOR ELECTRIC TRACTION MOTORS..

APPLICATION F I'LED1UNE 24,1912.

Patenmd June 13, 1916.

2711517752"? E JAaZz'wslffla/schke W uessea' I I II" I UNITED STATES PATENT OFFICE.-

JULIUS E. HASCHKE, OF CHICAGO, ILLINOIS.-

SPEED-CONTROL SYSTEM FOR ELECTRIC TRACTION-MOTORS.

Specification of Letters Patent.

Patentcd June 13, 1916.

Application filed June 24, 1912. Serial No. 705,420.

electric automobiles, launches and the like, but of course, mayhave. a more general ap- 15 plicatlon toelectr c tractionv service of any class where desired. The principa'l object of the invention is to provide an impro ved,' simple and reliable a. variable speed or torque is system of control by means ofwhich variable speed and torque may be obta-inedin aneffec'tive and etlicient manner.

More particularly, the object of the lnven- 'tion is to provide a system of control of g; the class described by means of which it is possible to utilize current from a, battery at- ;a, substantially constant potential, and to vary the speed of an electric motor without the insertion or removal of resistance pure and simple, from the circuit. I

further object of the invention is to 'provide a system of control of the class described-in which the field coils of amotor are wound in sections or are provided with suitable connection taps so that one or more corresponding sections of the field winding upon each pole may. be simultaneously cut out, whereby the speed and torque of the [motor may be varied.

a For the attainment of these ends andthe accomplishment of other new and useful objects, as 'Will appear, the invention conslats in the features of novelty in the COI1' structi'on, combination and arrangement of the several parts generally shown in the acout in the appended. claims.

In thedrawing, the figure is a diagram- 'matic representation of a speed control sys-' companying drawing and described'in thespecification, but'more particularly pointed.

tial, it is customary'to employ what known as a series parallel system or to control the speed of the motor by the insertion and removal of resistance or by a combinutioi'i of the two systems. A modification of either one or bothof these systems is commonly employed at the present time in controlling the speed of an electric car or more particularly an electric automobile. lVhen re sistance is inserted, there is a loss of power vdue to the resistance itself, which, of course,

is objectionable. In the series parallel sys tem, the storage battery is provided with a number of connections by means of which a current of reduced potential may be drawn from the battery or source of supply. This method of discharge is unsatisfactory because certain sections of thestorage battery are discharged in parallel.

It is the common practice to charge storage batteries in series and if they are discharged in parallel, it is almost impossible to discharge them equally for the reason that the controller contacts, by means of which the various battery connections are made, do not convey the currents with like conductivity, owing to the difference in pressure of the several contacts. Also the atmospheric conditions differ and the acid vapor formed has a dlfferent effect upon bat teries which have a free circulation of air and those which do not have such a free circulation thereby causing a difference in po- I tential of the different cells. This may come about from the fact that the different cells ferent sections of a battery are connected 1n parallel, a weaker sectlon will cause cross currents to flow between it and the stronger sections, thereby resulting in a loss of power and of efliciency. the present invention, the ,currentis drawn from the battery at the same potential under all circumstances and the current derived therefrom is discharged in the same way in which the battery is charged, that is, through all thecells connected in series, thereby preventing the unequal discharge ofcertain'cells and preventing heavy cross currents between sections of the battery when connected in parallel.

Referring now more particularly to. the drawing, the armature 1 of an electric motor is connected through a. double throw switch 2 in Series withv a storage battery 3 v The corresponding sections connected in series.

23 and 2 44am so the armfll' that." they will be projecting portion plate 27 through acontroller 4; andthrough the field coil windings of the motor. exei'nplification of isrepresented as field coils 5 and number of field coils may beemployed.

These field coils 5 and '6 are-provided with win'dingin correspondin sections the sections 7, 8 and 9 of-one' fie, d coil corresponding to the sections 10, 11 and 12 of the other. i are connected (1 the difiere'nt sections are all \Vhen the .field coils are-all connected in series, the circuit may be traced f rom a conductor 13, whiohconnectsone-of the field coils as lO to one side of the battery 3, through all of thewindings and by,'means o a conductor 1 4 to a 'suit-' able terminal of the controller 4.

The controller 4 comprises a 'terminal'QO to whichi s ,pivotally connected an arm 21'. A, plurality of contact members ,or' clips I 22, disposed with respect to engaged and electrical connection made therewith at different points in the rotation oft'he arm,- the arm remaining in contact with-each contact member after" it contacts with the succeed. ing one. Extending from tl1e-contact,ar-m 2Lis a projection which may be formed integral with the arm or secured ther'eto in any suitable manner." Disposed beneath 'this 25 is a bracket 26 in which a contact plate 27' is movable, This plate is )rovided' with a detent or'stop 28 adjustable by means of a screw 29, which is disposed in the path of movement of the projecting portion25 and a spring 30 is connected to the bracket '26 an'dto the plate 27 in such a manner as to tend to' press the plate outwardly at one end'of the bracket. The engagement of vthe projection with thedetent28 is operative when moved in one direction to retract the plate and 'when moved in the other directiom to permit the spring to act in moving it outwardly. 'Di sposed in the path of movement of the platev :is a holder 31 in which a conductor 32 is mounted. This conductor is preferably con structed, of some high-resistance material in' series I an such, for example, as carbon or the like, and

a 'holder is provided with an adjusting screw 33,1)? means of-which the position of the conductor- 32 may be adjusted. This conductor 32 is so disposed that the contact h will make electrical connection therewith when 'l)l18 i\1l11 9.1 is moved in a direction to permit the'spring 30 to; act in projecting the plate. The projection. 25 is so disposed that when the arm '21 is'move toward the contact members 2'2, and 24, the plate 27 will be allowed to contact before the electrical connection is made between the arm 2-1 and the contact 22 and also in moving the arm 21 in the other di-' conductor 34 and the 'cally connected to the terminal 20 by means drawing.

rent will pass directly is for the purpose of preventing arcin at 10 the tip' of the contact member 22 and a on'g the edge of the arm 21. The holder 31 is connected to the contact 22 bymeanso'f a bracket 26 is electriof a conductor. both of the conductors 34 and 35 be1n'g shown in dotted lines-in the The several parts and one of the, contact members as 23- and the conductor 37 forms connection between between thev double throw'switch 2 and the terminal 20.

of the field windings are connected in series by means of conductors :theconductor 15 and the other co'nt'act mem-v 8! her 24. .41 conductor 38 forms connection In operation,-, when it is desired to impel the motor in either direction,

isthrown in the desired direction and thearm 21 is, moved in the direction Of'the contact-members, tween the contact 32 and thecontact plate .27 and at approximately the same time mak-,' 'ing connectiomwith the contact member 22:,

first making connection bewhereupon a circuit is closed from one;- side of the battery to and through conductor '13,

coil 10, conductor 19, coil 7 conductor 15,

coil 8,'c0nductor 16, coil 11, coil 9', conductor ,18, coil 12, conductor 14, contact member 22, arm 21 terminal 20, conductor 38, switch 2, armature of the mmtor and to the other side of the battery.

Thus, it lwillbe seen that all of the sections" of the pole windings are connected in series and are also in series with the armature of the motor. It will also benoted that the coils and armature in series are connected across the battery so that the of the battery will be effective- By mov ing the arm. 21 further in the direction of the contacts until-electrical connection is made with the contact member-v.23, coils 9 and 12 will be-short-circuited and the c111- from coil 11 to 00n-v ductor 17, conductor36 and contact member 23 to the. ar m 2 1.' .Siinilarly, the further movement of the arm 21 in the same dim tion willshort-circuit coils 8 and 11, connection being made with the conductor 15- by means of the conductor 37 and the contact member 24 with the arm 21. Thus,'it will be seen that corresponding sections of each of the pole windings willv be short-circuited by the movemcnt ofthe contact arm 21. The current which flows through the coil windings and through the'armature Of the motor will thus be varied in accordance with the movement of the arm the switch 2 90 conductor 17, 1

full potential 1 21, resulting 1 ina correspondingchange of speed for each "the second .section of said ditt'erent' position the starting torque is of the arm.

will be obvious that although the present embodiment of the invention is described as having a motor with only two poles, there may be any desired number of poles with the corresponding coils .ofeach pole winding connected similarly to those shown and described in the present exemplification of the invention. The additional windings might either be in parallelor in series with the corresponding sections of the windings as shown, the object being to short-circuit the corresponding coil sections of each pole winding simultaneously. This results in a harmonious variation of of each pole since the current will be the same in each'one of the pole windings. The

armature of this motor is alwaysin series with the fields and since 'verylarge. If desired, the controller may be operated by means of the projecting portion 25 of the arm 21 or an additional connection 39may be provided to which a rodetO is secured and operated in any desired'or suitable manner.

lVhile I have thus described thepreferred embodiment of my invention, it is evident that others skilled in the art to which this relates, may make variouschanges in the construction, combination and arrangement of the several parts which constitute my invention, without departing from the spirit and scope thereof.

hat I- claim is: e

1. A speedcontrol system for electric motors comprising a motor havingfield coils,

each wound in Separate sections, the first section ofone of the field coils being con nected in series-with the first section in the other field coil, the last mentioned section being connected in series with the second and said second section of the second mentioned field coil being connected in series with first mentioned -1n engagement with the first .being connected in series with the pole strength.

it is a series motor,

.tWo subscribing Witn of June A.

860131011 of the second mentioned field coil field coil; acontact point connected with the second mentioned coil on the firstmentioned field; a. contact point connected to the first mentioned coil on the second mentioned field; and a member adapted to electrically engage said points successively and remain after engaging the second point. i

2. 'A speed control system for electric motors comprising a motor having field coils, each wound in separate sections, the first section of one of the field coils being. connected in series with the first section in the other field coil, the last mentioned section the second section of the second mentioned field coil and said second section of the second mentioned field coil being connected in series with the second section of said first mentioned field coil, the latter section being connected in series with the third section of the second mentioned field coil and the latter section being connected in series with the third section of said first mentioned field coil; a controller having contact points,-

one of such points being connected. with the first section of said points being connected section of said second section-field coil and another of said points being connected with the third section of the first mentioned field coil; and a member adapted to electrically engage each of said points successively and remain in engagement with the first point with the first and second gaging the third point. 7 In testimony whereof I have signed my name to thisspecification, in the presenceof sses, on this 21st day points after en- JULIUS E. HAsoHKE.

Witnesses:

CHARLES H. SEEM, KENT W. WOUNELL.

point engaged second point and 

